many hours of phone conversations overnight troubleshooting this problem...
as it turns out there was a encoder or comm. error during the initial Load Lock operation that users and I were unable to resolve over the phone. They had not noticed, nor reported to me during the phone calls, that the LLock door gate valve to the system chamber was still open. That interlock prevented users from venting the LLock to remove their samples.
Now checking I/O between the computers and resetting IEEE-488 bus and devices using it.
Ready for the next User.
JWC